A model system has been devised which monitors the adhesion of normal bovine lens epithelial cells to lens capsule, the native basement membrane upon which these cells rest in vivo. This system provides a favorable model for investigating the determinants involved in epithelial cell-basement membrane interactions. Using this method, in conjunction with a limited solubilization of the lens capsule by a procedure which employs solvent extraction rather than enzymatic treatment, it is possible to obtain subfractions of specific basement membrane glycoproteins of the lens capsule. One can then evaluate the role of these non-collagenous proteins in cellular adhesion and spreading in the lens cell-lens capsule attachment assay. Cellular adhesion and spreading on native basement membrane will be investigated using the epithelial cells of the anterior lens capsule obtained from primary cultures, early secondary cultures, and late passage cultures, as well as normal human fibroblasts and hamster tracheal epithelial cells. Test substrata will include native lens capsules, "residual" lens capsules, denatured types I and IV collagen and hydrated collagen gels in the presence or absence of basement membrane subfractions. The biological requirements for cell adhesion and spreading, will be studied, including a biochemical characterization of lens capsule structural components and the influence that native basement membrane exerts on cell ultrastructure and the expression of basement membrane constituents of adherent cells. A knowledge of the structural components of the lens capsule and the influence they may exert on lens epithelial cells normally attached thereto will advance our understanding of cell proliferation and differentiation and suggest ways to prevent or reverse the basement membrane related complications of diabetes and cataract formation.